Update handling of embedded palette data in image files.

[liblbx.git] / src / image.c

diff --git a/src/image.c b/src/image.c
index 336cd98ebd4951cfb049d24c10db6f3eeaf55864..4f1a2bd0c805e718f234c9ca92794058afcddb62 100644 (file)
--- a/src/image.c
+++ b/src/image.c
@@ -14,8 +14,9 @@
 
 struct lbx_image {
        uint16_t width, height;
-       uint16_t wtf1, wtf2;
+       uint16_t wtf1;
        uint16_t offs, frames;
+       uint16_t pal;
 
        FILE *f;
        long foff;
@@ -29,21 +30,31 @@ struct lbx_image {
 
 struct lbx_image *lbximg_fopen(FILE *f)
 {
-       struct lbx_image tmp = {.f = f}, *new;
+       struct lbx_image tmp = {.f = f}, *new = NULL;
 
        if (fread(&tmp.width,  sizeof tmp.width,   1, f) != 1) goto readerr;
        if (fread(&tmp.height, sizeof tmp.height,  1, f) != 1) goto readerr;
        if (fread(&tmp.wtf1,   sizeof tmp.wtf1,    1, f) != 1) goto readerr;
        if (fread(&tmp.offs,   sizeof tmp.offs,    1, f) != 1) goto readerr;
        if (fread(&tmp.frames, sizeof tmp.frames,  1, f) != 1) goto readerr;
-       if (fread(&tmp.wtf2,   sizeof tmp.wtf2,    1, f) != 1) goto readerr;
+       if (fread(&tmp.pal,    sizeof tmp.pal,     1, f) != 1) goto readerr;
 
        tmp.width  = letohs(tmp.width);  tmp.foff += sizeof tmp.width;
        tmp.height = letohs(tmp.height); tmp.foff += sizeof tmp.height;
        tmp.wtf1   = letohs(tmp.wtf1);   tmp.foff += sizeof tmp.wtf1;
        tmp.offs   = letohs(tmp.offs);   tmp.foff += sizeof tmp.offs;
        tmp.frames = letohs(tmp.frames); tmp.foff += sizeof tmp.frames;
-       tmp.wtf2   = letohs(tmp.wtf2);   tmp.foff += sizeof tmp.wtf2;
+       tmp.pal    = letohs(tmp.pal);    tmp.foff += sizeof tmp.pal;
+
+       /* For some reason, the format seems to need this. */
+       tmp.offs++;
+       tmp.frames++;
+
+       /* Format constraints. */
+       if (tmp.offs <= tmp.frames) {
+               lbx_errno = LBX_EFORMAT;
+               return NULL;
+       }
 
        /*
         * DEBUG ONLY.  These assertions exist to catch otherwise valid image
@@ -51,8 +62,9 @@ struct lbx_image *lbximg_fopen(FILE *f)
         * If we never find any exceptions, we can replace the assertions with
         * assumptions.
         */
-       assert(tmp.wtf1 == 0);
-       assert(tmp.offs == tmp.frames + 1);
+       _lbx_assert(tmp.wtf1 == 0);
+       _lbx_assert(tmp.offs == tmp.frames + 1);
+       _lbx_assert(tmp.pal  == 0 || tmp.pal == 0x1000);
 
        new = malloc(sizeof *new + tmp.offs * sizeof *new->offsets);
        if (!new) {
@@ -100,14 +112,14 @@ static int _lbx_drawrow(int first, struct lbx_image *img)
        if (type == 0) {
                if (fread(&yval,  sizeof yval,  1, img->f) != 1) goto readerr;
                yval = letohs(yval); img->foff += sizeof yval;
-
                if (yval == 1000)
                        return 1;
-
                if (fread(&count, sizeof count, 1, img->f) != 1) goto readerr;
                count = letohs(count); img->foff += sizeof count;
                if (fread(&xval,  sizeof xval,  1, img->f) != 1) goto readerr;
                xval = letohs(xval); img->foff += sizeof xval;
+               if (xval == 1000)
+                       return 1;
 
                /* Ensure that the row fits in the image. */
                if (img->height - img->currenty <= yval || xval >= img->width) {
@@ -211,7 +223,7 @@ unsigned char **lbximg_getframe(struct lbx_image *img, int frame)
                                return NULL;
                        first = 0;
 
-                       if (img->foff > img->offsets[frame+1]) {
+                       if (!rc && img->foff > img->offsets[frame+1]) {
                                lbx_errno = LBX_EFORMAT;
                                return NULL;
                        }
@@ -251,18 +263,38 @@ int lbximg_loadpalette(FILE *f, struct lbx_colour palette[static 256])
 int
 lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
 {
-       int index = 0;
+       size_t hdrlen = 6*(sizeof img->pal)+(img->offs)*(sizeof *img->offsets);
+       unsigned int i;
        size_t rc;
-       size_t hdrlen = 6*(sizeof img->width)
-                       + (img->offs)*(sizeof *img->offsets);
-       
-       uint8_t entry[4];
+
+       uint16_t zero, count;
+       uint8_t  entry[4];
+
+       /* Do nothing if the image doesn't have embedded palette data. */
+       if (img->pal == 0)
+               return 0;
 
        /* Palette data is located right after the header. */
        if (_lbx_fseek(img->f, &img->foff, hdrlen) == -1)
                return -1;
        
-       while (img->foff + sizeof entry <= img->offsets[0]) {
+       /* Palette header */
+       if (fread(&zero,  sizeof zero,  1, img->f) != 1) goto readerr;
+       if (fread(&count, sizeof count, 1, img->f) != 1) goto readerr;
+       zero  = letohs(zero);  img->foff += sizeof zero;
+       count = letohs(count); img->foff += sizeof count;
+
+       if (zero != 0 || count > 256) {
+               lbx_errno = LBX_EFORMAT;
+               return -1;
+       }
+
+       if (hdrlen + 2*(sizeof zero) + count*(sizeof entry) > img->offsets[0]) {
+               lbx_errno = LBX_EFORMAT;
+               return -1;
+       }
+
+       for (i = 0; i < count; i++) {
                rc = fread(entry, 1, sizeof entry, img->f);
                img->foff += rc;
 
@@ -270,13 +302,12 @@ lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
                        goto readerr;
                }
 
-               if (entry[0] == 0) {
-                       index++;
-               } else {
-                       index = entry[0];
+               if (entry[0] != 0) {
+                       lbx_errno = LBX_EFORMAT;
+                       return -1;
                }
 
-               palette[index] = (struct lbx_colour){
+               palette[i] = (struct lbx_colour){
                        .red   = entry[1] << 2,
                        .green = entry[2] << 2,
                        .blue  = entry[3] << 2,
@@ -285,13 +316,19 @@ lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
 
        return 0;
 readerr:
-       if (feof(img->f))
-               lbx_errno = LBX_EEOF;
-       else
-               lbx_errno = -errno;
+       lbx_errno = feof(img->f) ? LBX_EEOF : -errno;
        return -1;
 }
 
+void lbximg_getinfo(struct lbx_image *img, struct lbx_imginfo *info)
+{
+       *info = (struct lbx_imginfo) {
+               .width   = img->width,
+               .height  = img->height,
+               .nframes = img->frames,
+       };
+}
+
 void lbximg_close(struct lbx_image *img)
 {
        if (!img) return;